There are many different types of documents issued by government agencies that authorize the holder of such documents to perform authorized tasks or grant rights to the holder of such a document. Examples of such documents are driver's licenses, passports, entry access badges, identification cards and the like. In issuing such documents, it is desirable to have them of a convenient size, while including information necessary for identifying the holder and the rights conferred. With these two requirements, documents issued by government agencies not only will have a defined format, but the textual information printed thereon is dense, thereby leaving little or no room for any additional information to be printed thereon.
A problem frequently encountered by government officials is the forging of government issued documents. With the advent of computers and refined printers that are available at a relatively low cost, the incidence of forgery has proliferated. Although there are processes where coatings are applied to documents to prevent copying, this does not end with the problem of forgery. Various schemes have been proposed to provide security to government issued documents so as to inhibit forgeries of such documents. One such scheme is to use encryption so that a code can be derived that is based upon the information on the face of the government issued document. Unfortunately, because of the limited space normally available in such documents, such a scheme has proven unattainable. Clearly, it would be advantageous to provide a scheme for imparting security to a government issued document that would overcome the inhabitations caused by the predetermined size and defined format of such documents. Also, it would be advantageous to be able to carry hidden encrypted information and in determining authenticity to of the document.